Women who are night owls share the same high propensity for risk-taking as men, according to a recent study by a University of Chicago professor.
The research suggests that sleep patterns are linked with important character traits and behavior, said study author Dario Maestripieri, professor in Comparative Human Development. Night owls—people who tend to stay up late and wake up late in the morning—are different in many important ways from early risers, he found.
“Night owls, both males and females, are more likely to be single or in short-term romantic relationships versus long-term relationships, when compared to early birds,” Maestripieri said. “In addition, male night owls reported twice as many sexual partners than male early birds.”
The study, published in the February edition of the journal Evolutionary Psychology, draws on data from earlier research of more than 500 graduate students at the University of Chicago Booth School of Business. That initial study assessed financial risk aversion among male and female students and found men are more willing to take financial risks than women. Females with high testosterone levels, however, were more similar to males in financial risk-taking, that study found.
Maestripieri wanted to explore why men take more risks than women. He was curious whether sleep patterns have any influence on these tendencies, through an association with differences in personality and in novelty-seeking.
The study participants (110 males and 91 females) provided saliva samples to assess their levels of cortisol and testosterone. Those levels were measured before and after participants took a computerized test of their tendencies for financial risk aversion. The participants also described their own willingness to take risks and gave information about their sleep patterns.
Men had higher cortisol and testosterone levels than women; however, night-owl women had cortisol levels comparable to night-owl and early-morning men. Maestripieri’s study suggests high cortisol levels may be one of the biological mechanisms explaining higher risk-taking in night owls.
Maestripieri explains that some people have chronically high cortisol levels regardless of stress, which is known to increase cortisol for short periods of time. These people have high metabolism, high energy and arousability. Higher cortisol can be associated with higher cognitive function, he said, and some studies show that high-achieving, successful people have high cortisol levels.
More men than women consider themselves night owls, the study found, and men sleep less overall. Maestripieri said preferences for being a night owl or early morning person are due in part to biology and genetic inheritance, but also can be influenced by environmental factors such as shift work or child-rearing. Gender differences in sleep patterns emerge after puberty and become weaker or disappear after women reach menopause, Maestripieri said.
The link between the night-owl tendency and risky behavior could have roots in evolutionary strategies for finding mates, Maestripieri said.
“From an evolutionary perspective, it has been suggested that the night-owl trait may have evolved to facilitate short-term mating, that is, sexual interactions that occur outside of committed, monogamous relationships,” Maestripieri said. “It is possible that, earlier in our evolutionary history, being active in the evening hours increased the opportunities to engage in social and mating activities, when adults were less burdened by work or child-rearing.” The findings that night owls are less likely to be in long-term relationships and that male night owls report a higher number of sexual partners offer some support to this hypothesis, he said.
Maestripieri said he has replicated the main result of higher risk-taking in night owls with an expanded, non-student population and hopes to publish those findings soon.
According to a new study by researchers at Ben-Gurion University of the Negev (BGU) and the University of Amsterdam, oxytocin caused participants to lie more to benefit their groups, and to do so more quickly and without expectation of reciprocal dishonesty from their group. Oxytocin is a hormone the body naturally produces to stimulate bonding.
The research was published this week in the Proceedings of the National Academy of Science (PNAS).
“Our results suggest people are willing to bend ethical rules to help the people close to us, like our team or family,” says Dr. Shaul Shalvi of Ben-Gurion University of the Negev’s Department of Psychology and director of BGU’s Center for Decision Making and Economic Psychology. “This raises an interesting, although perhaps more philosophical, question: Are all lies immoral?”
Dr. Shalvi’s research focuses on ethical decision-making and the justifications people use to do wrong and still feel moral. Specifically, he looks at what determines how much people lie and which settings increase people’s honesty. Very little is known about the biological foundations of immoral behavior.
“Together, these findings fit a functional perspective on morality revealing dishonesty to be plastic and rooted in evolved neurobiological circuitries, and align with work showing that oxytocin shifts the decision-maker’s focus from self to group interests,” Shalvi says.
“The results highlight the role of bonding and cooperation in shaping dishonesty, providing insight into when and why collaboration turns into corruption.”
Oxytocin is a peptide of nine amino acids produced in the brain’s hypothalamus, functioning as both a hormone and neurotransmitter. Research has shown that in addition to its bonding effect in couples and between mothers and babies, it also stimulates one’s social approach.
Higher levels of oxytocin correlate with greater empathy, lower social anxiety and more pro-social choice in anonymous games; reduction in fear response; and greater trust in interpersonal exchange. It also stimulates defense-related aggression.
In the experiment designed by Shalvi and fellow researcher Carsten K. W. De Dreu of the University of Amsterdam’s Department of Psychology, 60 male participants received an intranasal dose of either oxytocin or placebo. They were then split into teams of three and asked to predict the results of 10 coin tosses.
Participants were asked to toss the coin, see the outcome and report whether their prediction was correct. They knew that for each correct prediction, they could lie and earn more money to split between their group members, who were engaging in the same task.
“The statistical probability of someone correctly guessing the results of nine or 10 coin tosses is about one percent,” says Shalvi. “Yet, 53 percent of those who were given oxytocin claimed to have correctly predicted that many coin tosses, which is extremely unlikely.”
Only 23 percent of the participants who received the placebo reported the same results, reflecting a high likelihood that they were also lying, but to a lesser extent compared to those receiving oxytocin.
The ability to stay positive when times get tough – and, conversely, of being negative – may be hardwired in the brain, finds new research led by a Michigan State University psychologist.
The study, which appears in the Journal of Abnormal Psychology, is the first to provide biological evidence validating the idea that there are, in fact, positive and negative people in the world.
“It’s the first time we’ve been able to find a brain marker that really distinguishes negative thinkers from positive thinkers,” said Jason Moser, lead investigator and assistant professor of psychology.
For the study, 71 female participants were shown graphic images and asked to put a positive spin on them while their brain activity was recorded. Participants were shown a masked man holding a knife to a woman’s throat, for example, and told one potential outcome was the woman breaking free and escaping.
The participants were surveyed beforehand to establish who tended to think positively and who thought negatively or worried. Sure enough, the brain reading of the positive thinkers was much less active than that of the worriers during the experiment.
“The worriers actually showed a paradoxical backfiring effect in their brains when asked to decrease their negative emotions,” Moser said. “This suggests they have a really hard time putting a positive spin on difficult situations and actually make their negative emotions worse even when they are asked to think positively.”
The study focused on women because they are twice as likely as men to suffer from anxiety related problems and previously reported sex differences in brain structure and function could have obscured the results.
Moser said the findings have implications in the way negative thinkers approach difficult situations.
“You can’t just tell your friend to think positively or to not worry – that’s probably not going to help them,” he said. “So you need to take another tack and perhaps ask them to think about the problem in a different way, to use different strategies.”
Negative thinkers could also practice thinking positively, although Moser suspects it would take a lot of time and effort to even start to make a difference.
His co-researchers were former or current MSU psychology students Rachel Hartwig, Tim Moran and Alexander Jendrusina; and University of Michigan researcher Ethan Kross.
A new translation of a 6-foot-tall calcite block called the Tempest Stela suggests the Egyptian pharaoh Ahmose ruled at a time 30 to 50 years earlier than previously thought—a finding that could change scholars’ understanding of a critical juncture in the Bronze Age.
An inscription on a 3,500-year-old stone block from Egypt may be one of the world’s oldest weather reports—and could provide new evidence about the chronology of events in the ancient Middle East, writes Susie Allen and William Harms in UChicago News
A new translation of a 40-line inscription on the 6-foot-tall calcite block called the Tempest Stela describes rain, darkness and “the sky being in storm without cessation, louder than the cries of the masses.”
Two scholars at the University of Chicago’s Oriental Institute believe the unusual weather patterns described on the slab were the result of a massive volcano explosion at Thera—the present-day island of Santorini in the Mediterranean Sea. Because volcano eruptions can have a widespread impact on weather, the Thera explosion likely would have caused significant disruptions in Egypt.
The new translation suggests the Egyptian pharaoh Ahmose ruled at a time closer to the Thera eruption than previously thought—a finding that could change scholars’ understanding of a critical juncture in human history as Bronze Age empires realigned. The research from the Oriental Institute’s Nadine Moeller and Robert Ritner appears in the spring issue of the Journal of Near Eastern Studies.
The Tempest Stela dates back to the reign of the pharaoh Ahmose, the first pharaoh of the 18th Dynasty. His rule marked the beginning of the New Kingdom, a time when Egypt’s power reached its height. The block was found in pieces in Thebes, modern Luxor, where Ahmose ruled.
If the stela does describe the aftermath of the Thera catastrophe, the correct dating of the stela itself and Ahmose’s reign, currently thought to be about 1550 B.C., could actually be 30 to 50 years earlier.
“This is important to scholars of the ancient Near East and eastern Mediterranean, generally because the chronology that archaeologists use is based on the lists of Egyptian pharaohs, and this new information could adjust those dates,” said Moeller, assistant professor of Egyptian archaeology at the Oriental Institute, who specializes in research on ancient urbanism and chronology.
In 2006, radiocarbon testing of an olive tree buried under volcanic residue placed the date of the Thera eruption at 1621-1605 B.C. Until now, the archeological evidence for the date of the Thera eruption seemed at odds with the radiocarbon dating, explained Oriental Institute postdoctoral scholar Felix Hoeflmayer, who has studied the chronological implications related to the eruption. However, if the date of Ahmose’s reign is earlier than previously believed, the resulting shift in chronology “might solve the whole problem,” Hoeflmayer said.
The revised dating of Ahmose’s reign could mean the dates of other events in the ancient Near East fit together more logically, scholars said. For example, it realigns the dates of important events such as the fall of the power of the Canaanites and the collapse of the Babylonian Empire, said David Schloen, associate professor in the Oriental Institute and Near Eastern Languages & Civilizations on ancient cultures in the Middle East.
“This new information would provide a better understanding of the role of the environment in the development and destruction of empires in the ancient Middle East,” he said.
For example, the new chronology helps to explain how Ahmose rose to power and supplanted the Canaanite rulers of Egypt—the Hyksos—according to Schloen. The Thera eruption and resulting tsunami would have destroyed the Hyksos’ ports and significantly weakened their sea power.
In addition, the disruption to trade and agriculture caused by the eruption would have undermined the power of the Babylonian Empire and could explain why the Babylonians were unable to fend off an invasion of the Hittites, another ancient culture that flourished in what is now Turkey.
‘A TEMPEST OF RAIN’
Some researchers consider the text on the Tempest Stela to be a metaphorical document that described the impact of the Hyksos invasion. However, Ritner’s translation shows that the text was more likely a description of weather events consistent with the disruption caused by the massive Thera explosion.
Ritner said the text reports that Ahmose witnessed the disaster—the description of events in the stela text is frightening.
The stela’s text describes the “sky being in storm” with “a tempest of rain” for a period of days. The passages also describe bodies floating down the Nile like “skiffs of papyrus.”
Importantly, the text refers to events affecting both the delta region and the area of Egypt further south along the Nile. “This was clearly a major storm, and different from the kinds of heavy rains that Egypt periodically receives,” Ritner said.
In addition to the Tempest Stela, a text known as the Rhind Mathematical Papyrus from the reign of Ahmose also makes a special point of mentioning thunder and rain, “which is further proof that the scholars under Ahmose paid close and particular attention to matters of weather,” Ritner said.
Marina Baldi, a scientist in climatology and meteorology at the Institute of Biometeorology of the National Research Council in Italy, has analyzed the information on the stela along with her colleagues and compared it to known weather patterns in Egypt.
A dominant weather pattern in the area is a system called “the Red Sea Trough,” which brings hot, dry air to the area from East Africa. When disrupted, that system can bring severe weather, heavy precipitation and flash flooding, similar to what is reported on the Tempest Stela.
“A modification in the atmospheric circulation after the eruption could have driven a change in the precipitation regime of the region. Therefore the episode in the Tempest Stela could be a consequence of these climatological changes,” Baldi explained.
Other work is underway to get a clearer idea of accurate dating around the time of Ahmose, who ruled after the Second Intermediate period when the Hyksos people seized power in Egypt. That work also has pushed back the dates of his reign closer to the explosion on Thera, Moeller explained.
- See more at: http://news.uchicago.edu/article/2014/04/01/world-s-oldest-weather-report-could-revise-bronze-age-chronology#sthash.rREfzxTD.dpuf
After looking at 1.1 million online reviews for 840,000 restaurants in more than 32,000 cities across the country, Georgia Tech and Yahoo Labs researchers have found that the weather outside can be just as significant a factor for reviews as what happens inside a restaurant. Their study shows evaluations written on rainy or snowy days, or very cold or hot days, are more negative than those written on nice days.
“People love to describe themselves as foodies. But in the end, it looks like we’re all weather people, whether we realize it or not,” said Saeideh Bakhshi, a Georgia Tech College of Computing Ph.D. candidate who led the study.
The study also found a nationwide spike in the number of reviews written during the summer, but July and August were the worst months of the year for ratings. November was the best.
“The best reviews are written on sunny days between 70 and 100 degrees,” said Bakhshi. “Science has shown that weather impacts our mood, so a nice day can lead to a nice review. A rainy day can mean a miserable one.”
The study covered a period of 10 years of reviews on sites that included Foursquare, Citysearch and TripAdvisor. It also found that demographic factors such as neighborhood diversity, education levels and population density have a significant impact.
For instance, areas with a high percentage of people with college degrees (more than 50 percent) average nearly three times more reviews than places where fewer than 10 percent have diplomas. However, higher education levels don’t have much of an effect on ratings.
The study shows that population density of cities is closely tied to the expectations of service options. Based on reviews in busy cities, people are more patient with wait times and expect restaurants to have delivery options. In smaller cities, carryout service was rated more positively than places with delivery, but reviewers were harsher on pace of service.
“We also found that restaurants in the Northeast and Pacific get more reviews than places in the South and Midwest,” Bakhshi added. “I think the difference between the South and Pacific comes mostly from the differences in education, diversity and liberal versus conservative. Blue states such as California, Washington and Oregon have a higher number of reviews per restaurant.”
The research team also included Eric Gilbert, an assistant professor in Georgia Tech’s School of Interactive Computing, and Partha Kanuparthy, a Yahoo Labs research scientist and 2012 Ph.D. Georgia Tech graduate in computer science.
“Our findings could help consumers better understand online reviews and ratings and help review sites calibrate recommendations,” said Gilbert. “Outside factors apparently introduce bias in online ratings of a highly reviewed restaurant in big cities compared to a similar place in a rural area.”
As for the ultimate “outside factor,” Kanuparthy says restaurants face the same challenge as everyone else.
“You can plan the best wedding or birthday party. Restaurants can serve great food and provide spectacular service,” he notes. “But no one can control the weather. In the end, you can’t beat Mother Nature.”
Despite knowing that buying life experiences will make them happier than buying material items, shoppers might continue to spend money on the latter because they mistakenly believe items are a better value, according to a San Francisco State University study published today. That belief, however, isn’t accurate.
Those surveyed after making a purchase rated life experiences both making them happier and as a better use of their money, indicating many are sacrificing their well-being for a sense of value that never materializes. The study is one of the first to shed light on why people buy material items even though years of research has shown experiences provide a greater happiness boost.
“People actually do know, and accurately predict, that life experiences will make them happier,” said SF State Associate Professor of Psychology Ryan Howell, a co-author of the study who has extensively researched the link between spending and happiness. “What they really underestimate is how much monetary value they will get out of a life experience. Even though they’re told experiences will make them happier and they know experiences will make them happier, they still perceive material items as being a better value.”
Part of the reason, Howell suggests, is that material items are a tangible reminder of what the item is worth. Life experiences produce only memories, which can be harder to put a price tag on.
“We naturally associate economic value with stuff. I bought this car, it’s worth $8,000,” he said. “We have a hard time estimating the economic value we would place on our memories.”
To conduct the study, Howell and lead author Paulina Pchelin, a student at SF State when the research took place, surveyed individuals both before and after making a purchase. Prior to the purchase, respondents said they believed a life experience would make them happier but a material item would be a better use of their money. After the purchase, however, respondents reported that life experiences not only made them happier but were also the better value.
“There were just huge underestimates in how much value people expected to get from their purchase,” Howell said. “It’s almost like people feel they will get no economic value from their life experiences and therefore they feel this tension in spending money on them.”
Adjusting an individual’s priorities, the study showed, can change spending behavior. In an additional experiment, those asked to prioritize value when making a purchase gravitated toward material items, while those asked to prioritize happiness chose experiences.
Determining the best way to encourage the general public to prioritize happiness over value will require additional research, Howell said. The implications, however, extend far beyond the realm of psychology or even retail.
“Happiness is not some fleeting, positive emotion we experience in the moment,” he said. “There are tremendous benefits to happiness. Companies want their employers to be happier because they are more productive. Doctors want their patients to be happier because they will be healthier. We should try to figure out how to help people maximize their happiness because of all the benefits that come from it.” As next step, Howell is inviting people to forecast their happiness from consumer items by taking part in studies on his website BeyondThePurchase.Org.
“The Hidden Cost of Value-seeking: People do not Accurately Forecast the Economic Benefits of Experiential Purchases,” by Paulina Pchelin and Ryan T. Howell was published online April 2 in the Journal of Positive Psychology.
Men who started smoking regularly before the age of 11 had sons who, on average, had 5-10kg more body fat than their peers by the time they were in their teens, according to new research from the Children of the 90s study at the University of Bristol. The researchers say this could indicate that exposure to tobacco smoke before the start of puberty may lead to metabolic changes in the next generation.
The effect, although present, was not seen to the same degree in daughters. Many other factors, including genetic factors and the father’s weight, were taken into account but none could explain the change. In fact, the fathers who started smoking before 11 tended to have lower BMIs (body mass index) on average.
The effect was not seen in the sons of men who started smoking after the age of 11, suggesting that the period before the start of puberty is a particularly sensitive period for environmental exposures. This is in line with a prior hypothesis by the authors based on earlier Swedish studies that linked paternal ancestor’s food supply in mid childhood with mortality rates in grandchildren.
Of the 9,886 fathers enrolled in the study, 5,376 (54 per cent) were smokers at some time and, of these, 166 (3 per cent) reported smoking regularly before the age of 11.
When measured at age 13, 15 and 17, the sons of the men in the latter category had the highest BMIs at each time point compared with the sons of men who had started smoking later or who had never smoked. More precisely, these boys had markedly higher levels of fat mass (recorded using whole-body scans), ranging from an extra 5kg to 10kg between ages 13 and 17.
The research was funded by the UK Medical Research Council (MRC) and is published today [2 April 2014] in the European Journal of Human Genetics.
Speaking about the findings, senior author, Professor Marcus Pembrey said:
‘This discovery of trans-generational effects has big implications for research into the current rise in obesity and the evaluation of preventative measures. It is no longer acceptable to just study lifestyle factors in one generation. We are probably missing a trick with respect to understanding several common diseases of public health concern by ignoring the possible effects of previous generations.’
Professor David Lomas, Chair of the MRC’s Population and Systems Medicine Board, added:
‘Population studies have provided a wealth of information about health and disease, including first identifying the link between smoking and cancer more than 60 years ago. This research clearly demonstrates that such studies have so much more to give, which is why it’s vital that the future potential of cohorts and the studies they make possible is not jeopardised by the proposed EU data regulations.’
Mounted Neanderthal skeleton, American Museum of Natural History
Although Neanderthals are extinct, fragments of their genomes persist in modern humans.
These shared regions are unevenly distributed across the genome and some regions are particularly enriched with Neanderthal variants. An international team of researchers led by Philipp Khaitovich of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and the CAS-MPG Partner Institute for Computational Biology in Shanghai, China, show that DNA sequences shared between modern humans and Neanderthals are specifically enriched in genes involved in the metabolic breakdown of lipids. This sharing of genes is seen mainly in contemporary humans of European descent and may have given a selective advantage to the individuals with the Neanderthal variants.
The researchers analyzed the distribution of Neanderthal variants in the genomes of eleven contemporary human populations of African, Asian and European descent. They found that genes involved in the lipid synthesis contained a particularly high number of Neanderthal variants in contemporary humans of European origin, but not in Asians and Africans. “These sequences show signs of recent positive selection”, says Philipp Khaitovich of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and the CAS-MPG Partner Institute for Computational Biology in Shanghai, China. “This may indicate that they give modern humans carrying the Neanderthal genotype a selective advantage.”
Analyzing the influence of Neanderthal variants on lipid processing in modern humans, the researchers further found recent evolutionary changes in lipid concentration and expression of metabolic enzymes in brains of humans of European origin. “We don’t know what these lipid concentration changes do to the brain, but the fact that Neanderthal variants might have changed our brain composition has interesting implications”, says Philipp Khaitovich. Further work is needed, however, in order to fully assess the potential functional effects of these changes.
UC Davis scientists have learned why zebras, like these plains zebras in Katavi National Park, Tanzania, have stripes. Credit: Tim Caro/UC Davis
Why zebras have black and white stripes is a question that has intrigued scientists and spectators for centuries. A research team led by the University of California, Davis, has now examined this riddle systematically. Their answer is published in the online journal Nature Communications.
The scientists found that biting flies, including horseflies and tsetse flies, are the evolutionary driver for zebra’s stripes. Experimental work had previously shown that such flies tend to avoid black-and-white striped surfaces, but many other hypotheses for zebra stripes have been proposed since Alfred Russel Wallace and Charles Darwin debated the problem 120 years ago. These include:
A form of camouflage
Disrupting predatory attack by visually confusing carnivores
A mechanism of heat management
Having a social function
Avoiding ectoparasite attack, such as from biting flies
The team mapped the geographic distributions of the seven different species of zebras, horses and asses, and of their subspecies, noting the thickness, locations, and intensity of their stripes on several parts of their bodies. Their next step was to compare these animals’ geographic ranges with different variables, including woodland areas, ranges of large predators, temperature, and the geographic distribution of glossinid (tsetse flies) and tabanid (horseflies) biting flies. They then examined where the striped animals and these variables overlapped.
After analyzing the five hypotheses, the scientists ruled out all but one: avoiding blood-sucking flies.
“I was amazed by our results,” said lead author Tim Caro, a UC Davis professor of wildlife biology. “Again and again, there was greater striping on areas of the body in those parts of the world where there was more annoyance from biting flies.”
While the distribution of tsetse flies in Africa is well known, the researchers did not have maps of tabanids (horseflies, deer flies). Instead, they mapped locations of the best breeding conditions for tabanids, creating an environmental proxy for their distributions. They found that striping is highly associated with several consecutive months of ideal conditions for tabanid reproduction.
Why would zebras evolve to have stripes whereas other hooved mammals did not? The study found that, unlike other African hooved mammals living in the same areas as zebras, zebra hair is shorter than the mouthpart length of biting flies, so zebras may be particularly susceptible to annoyance by biting flies.
“No one knew why zebras have such striking coloration,” Caro said. “But solving evolutionary conundrums increases our knowledge of the natural world and may spark greater commitment to conserving it.”
Yet in science, one solved riddle begets another: Why do biting flies avoid striped surfaces? Caro said that now that his study has provided ecological validity to the biting fly hypothesis, the evolutionary debate can move from why zebras have stripes to what prevents biting flies from seeing striped surfaces as potential prey, and why zebras are so susceptible to biting fly annoyance.